Installing and Administering PPP

84 Chapter 4
Common pppd Options
IP Routing Tips
arp -s nomad 8:0:9:30:dc:91 pub
(The hexadecimal sequence 8:0:9:30:dc:91 is the Mac address of the
Ethernet card in alpha. Substitute the Mac address for your machine’s
Ethernet card in the command above.) This would add a permanent
entry to alpha’s ARP table, and cause it to be provided to other systems
on the local Ethernet. Any time a host on that LAN tries to find the
Ethernet address corresponding to nomad’s IP address, the request will
be answered with instructions to forward the packets to alpha. Since
nomad appears to be directly connected to the LAN, no hosts on the LAN,
nor on any other IP-connected network, would require routing table
modifications.
Connecting Two LANs
Suppose gate-a (192.9.200.63) and ws-a (192.9.200.66) are on one LAN,
with gate-a supporting a modem. Also suppose gate-b (134.19.14.29) and
ws-b (134.19.14.102) are on another LAN across town, with gate-b
supporting a modem.
Figure 4-3
gate-b’s pppd should be started as
pppd gate-b:gate-a auto idle 130
and gate-b should have a route like
route add net 192.9.200.0 gate-a 1
ws-b should have a route like
route add net 192.9.200.0 gate-b 1
Similarly, gate-a’s pppd should be started as
pppd gate-a:gate-b auto idle 130
and gate-a should have a route like
route add net 134.19.14.0 gate-b 1
or, depending upon the structure of LAN b, maybe